Democrats haven’t fielded a competitive opponent against Wisconsin Rep. Paul Ryan in years.

But now, as they are trying to paint the rising GOP star as a bogeyman because of his plan to overhaul Medicare, an effort is being made by Democrats to run a serious challenger against him in 2012.

Cue Rob Zerban, a Democrat Kenosha County Board supervisor running for the seat, who summed up his campaign message in Milwaukee this weekend: “My opponent not only endorses the plan to end Medicare. He wrote the plan.”

In an attempt to alienate Paul from seniors, Zerban has launched a website called “handsoffmygrandma.com.”

Ryan’s “Path to Prosperity” plan would revamp Medicare, allowing seniors to use a “premium support” system to purchase health care in a private market. The Wisconsin congressman has said Medicare is on the verge of collapse, is unsustainable and will vanish if nothing is done to it.

Ryan was elected to Congress in 1998. He took a pass on running for an open Wisconsin senate seat this year and has not succumbed to the pressures of activists and conservative writers begging him to run for president in 2012.

He has won re-election easily in past years, despite coming from a swing district that President Obama carried in 2008 with 51 percent of the vote. In 2004, President George W. Bush won there with 53 percent. Republicans are downplaying the notion that he’s more vulnerable.

“Despite the Democrats’ best attempts, Paul Ryan’s willingness to take on Washington’s spending addiction has never been a political liability for him in a competitive district,” said Andrea Bozek, a regional press secretary for the National Republican Congressional Committee.

In a statement to The Daily Caller, Ryan’s campaign manager, Susan Jacobson, said the congressman’s “focus right now is on doing his job representing his employers in Congress and preventing a national debt crisis, not on campaigning for the next election.”

Zerban, a small business owner, has so far enjoyed supportive words from national Democrats, who have listed Paul as one of 50 vulnerable Republican members of Congress in its “Drive to 25” campaign.

DCCC Chair Steve Israel told the liberal Huffington Post that he thinks Ryan’s seat is “one district where the political landscape may change” and that Zerban is an “excellent” candidate who “got into the race largely because he couldn’t tolerate Paul Ryan’s leadership on a plan to terminate Medicare.”

Zerban prominently displays Israel’s words on his website’s homepage.

Democratic Party of Wisconsin chairman Mike Tate acknowledged that Democrats have not “fielded strong candidates in the past” against Ryan, but said this year will be different.

“Rob brings a tremendous profile to this race … couple that with Paul Ryan and his extremist plan. We could be seeing a perfect storm here,” he said to the Journal Times.